Austempering technology is a driving force behind the strategic development in the iron foundry market.
ADI – Austempered Ductile Iron is a material that offers the combination of high fatigue resistance, wear resistance, toughness, lightness and extensive freedom in designing components together with good machining properties.
Through the iron casting process combined with the heat treatment, the mechanical properties achieved are the typical one of quenched&tempered steel. Austempered ductile iron (ADI) is an excellent opportunity to achieve ambitious goals to lighten and reduce the total production cost of the component.
According these properties, during EcoMetals tour we present two important case histories:
First case history: introducing ADI in automotive suspension system converting existing ductile iron solution in ADI casting solution
Customer designs and produces suspension modules and components for motor vehicles.
Objective of improvement: the aim of ADI introduction was to take advantage of its higher material properties towards lightweight, at reasonable industrial costs. -20% weight reduction.
Previous knuckle and previous control arm in ductile iron material (Rm=600 Mpa) had a consolidated foundry process. ADI900-8 casting solution, first of all, it didn’t generate relevant impact in casting process, just a little change on chemical composition then ADI permitted to obtain a relevant weigh saving.
So at the end of this project, the customer chose ADI and obtain the following advantages:
Weight reduction (about 8,00kg less for vehicles)
Reduction of fuel consumption
Second case history - Replacement of a welding structure with an Austempered Ductile Iron (ADI) one. Customer is specialized in design, production and selling of trailers, semi-trailers and self-propelled vehicles for heavy transportation.
Objective of improvement: +25% axle load maintaining the same weight
Existing welded structure had some weak points: more complex welding process(pre-heating, …), stress concentrations due to geometry (notch effects) that can generate early fatigue phenomena and a possible relevant increase of weigh. Benefits: low investments in production and assembly tools.
ADI800-10 casting solutions offered good benefits: increase of load capacity of 25 % with no increase of weight, part more accurate and repeatable, increasing of fatigue life due to reduction of notch effects, shape with less constrains and reduction of components. The only weak point for casting solution was tooling cost.
At the end, Customer chose ADI casting solution for:
- Increase payload (from 40 t to 50 t per axle, +25%)
- maintaining the same weight
- Reduction of fuel consumption (the alternative solution in steel needed an relevant increase of weight).
About Zanardi Fonderie S.p.a.
Zanardi Fonderie S.p.a. is an italian foundry specialised in the development and production of spheroidal graphite iron (GJS) and austempered ductile iron (ADI). Thanks to our robust integrated process, the products are designed and produced on-site in the company’s factory in Minerbe (Verona). The process includes also the austempering heat treatment department with three AFC-Holcroft UBQA 36-72-36 furnaces which allow excellent results to be achieved in terms of process repeatability. Zanardi can treat castings of up to 840x1705x890 mm in size, weighing up to 1.000 kg and different batches, from small series to large-scale automotive production.
In 2019, Zanardi Fonderie established the new “Zanardi Austempering” brand to offer all foundries a third-party heat treatment service and act as a single reference point for the conception, design, development and certification of the material. “Zanardi Austempering” offers the market all ADI grades in compliance with the international standards (ISO17804, EN1564 and ASTMA897/A897M), as well as other material grades, such as Austempered Grey Iron (AGI) and austempered steel. It also makes the company’s latest patented technology available to foundries: the IDI grade (Isothermed Ductile Iron).